Injection syringe with movable needle protector

ABSTRACT

The invention concerns an injection syringe (10) comprising a syringe body (12) bearing an injecting needle (22) and a rear actuating piston (14) movably mounted in the body (12). It further comprises a mobile protector (36) of the end (22A) of the injecting needle, movable between a retracted position in the body (12) and an active protecting position in which the front end or the protector (36) is in front of the injecting end (22A). The protector (36) and the syringe body (12) comprise protuberances associated (44, 102) by projections and recesses for maintaining the protector (36) in its active protecting position. The syringe comprises a member (66) for positively retaining in locked position the protuberances associated (44, 102) by projections and recesses when the needle protector (36) is in active protecting position.

The present invention concerns an injection syringe of the type whichincludes, on the one hand, an elongate syringe body comprising a tubeand a front wall equipped with an injection needle, and, on the otherhand, a rear actuating plunger which is mounted so as to be displaceablein the tube, which syringe additionally includes a mobile protector, forthe injection end of the needle, displaceable between a retractedposition in the syringe body, behind the injection end of the needle,and an active protection position in which the front end of theprotector is situated in front of the injection end of the needle, theprotector and the syringe body including associated projecting andrecessed reliefs for maintaining the protector in its active protectionposition.

A syringe of this type is described, for example, in the document U.S.Pat. No. 5,370,628.

In this document, the mobile protector for the injection end of theneedle includes legs penetrating inside the syringe.

The legs include means for snap-locking on the body of the syringe inorder to maintain the protector in its active protection position.

However, these snap-locking means afford a relatively weak force forholding the protector. Thus, an axial stress exerted on the protectorcan cause retraction of the latter inside the syringe body. Suchretraction of the protector once more exposes the injection end of theneedle, thereby causing risks of accidental stick injuries.

Thus, in the known syringes, the protection of the end of the needle bythe protector is unreliable, as the protector can quite easily be pushedback into its retracted position.

The object of the invention is to make available a solution to thisproblem, in particular limiting the risks of accidental return of theprotector to its retracted position.

To this end, the subject of the invention is a syringe of theaforementioned type, characterized in that it includes, inside thesyringe body, a member for positive retention of the engagement of thesaid associated projecting and recessed reliefs when the needleprotector is in its active protection position.

The invention will be better understood from reading the followingdescription which is given solely by way of example and in whichreference is made to the drawings, in which:

FIG. 1 is a longitudinal cross section through a syringe according tothe invention, before use;

FIG. 2 is a detail, on a larger scale, of the zone surrounding the rearend of the needle of the syringe in FIG. 1;

FIGS. 3 to 6 are longitudinal cross sections through the syringe in FIG.1, at different successive stages of use of the syringe,

FIG. 7 is a detail, on a larger scale, of the zone surrounding the frontwall of the syringe after completion of the injection, and

FIGS. 8 and 9 are detailed side views of means provided between thesyringe body and the rear actuating plunger.

The injection syringe 10 represented in FIG. 1, with general form ofrevolution about axis X--X, is a disposable syringe. It is offered readyfor use and already containing a medical fluid to be injected. Itessentially includes an elongate syringe body 12 and a rear actuatingplunger 14 which is mounted so as to be displaceable inside the body 12.

The syringe body 12 is formed by a tube 16 at the front end of whichthere is fixed a needle holder 18 which bears a front wall 20 of thesyringe body. This front wall 20 is equipped with an injection needle 22passing through it. The latter includes a front injection end 22Aprojecting from the body. The needle continues axially inside the body12 as far as a rear or proximal end 22B. The portion of the needleextending inside the syringe body is longer than the section of theneedle projecting outside the syringe body.

The tube 16 is made of glass, for example, and has a circular crosssection. Its front end is equipped externally with a peripheral flange24 for holding the needle holder 18. Likewise, at its rear end, the tube16 includes externally a peripheral flange 24A. Attached to this rearend there is a grip member 25 which facilitates gripping of the syringebody between the index finger and the middle finger. This grip member 25includes a sleeve 26 snapped externally onto the end of the tube 16 onthe flange 24A, and two diametrically opposite tabs 27 for supportingthe fingers.

The needle holder 18 is delimited externally by a sleeve 28. The frontwall 20 is made in one piece with the sleeve 28 and extends transverselyat an intermediate point of the latter. Formed on the inner wall of thesleeve 28, slightly behind the front wall 20, there is a peripheralgroove 30 for receiving the flange 24.

The front wall 20 has an axial stud 32, integral therewith, for fixingthe injection needle 22. This stud is directed towards the injection end22A of the needle and is received inside the space delimited by thesleeve 28.

Three identical openings 34 are made through the front wall 20. They aredistributed at uniform angles around the stud 28 on one and the samecircular contour and have an arc shape. The figures are longitudinalcross sections of the syringe made on either side of the axis X--X inthe middle part of two of the openings 34.

These openings 34 provide for the passage and guiding of a needleprotector 36. The latter includes, at the front, a protection ring 38made of rigid plastic, of which the internal and external diameters areadapted so that the ring 38 lodges in the annular space defined betweenthe stud 32 and the sleeve 18. This ring is continued by three identicallegs 40 which are elastically deformable and are spaced angularly at120°. These legs 40 have, in cross section, a slight curvaturecorresponding to that of the ring 38 and they have a lengthsubstantially equal to the length of that portion of the needle 22received in the syringe body 12.

Furthermore, each leg 40 includes, over its entire width, a firstinternal bulge 42 arranged slightly to the rear of the ring 38, and asecond external bulge 44 arranged at its free end.

In addition, as is represented in FIG. 2, the legs 40 include, in thevicinity of their free ends, an internal recess 46 with cylindrical baseextending the entire width of each leg. On each leg, this recess 46 isdelimited, at the front, by a shoulder 48 formed in the thickness of theleg and, at the rear, by a projection 50 formed in the area of the bulge44. Each projection 50 carries a cam surface 52 formed by asubstantially circular curved surface connecting the rounded summit ofthe projection 50 to the base of the recess 46.

Means 64 for axial guiding of the rear end 22B of the needle are heldbetween the free ends of the legs 40. These means include a member 66 ofrevolution held between the legs 40. This member is made of a rigidmaterial, in particular a rigid plastic material. It includes on theoutside, to the rear, a truncated lateral wall 68. It is borderedexternally, to the front, by a collar 70. The cylindrical lateralsurface of the collar 70 is hollowed out, at its centre viewed in thedirection of the axis X--X, with a shallow peripheral groove 71. Thedepth of the groove is in particular less than the height of the bulges44. Before use of the syringe (FIGS. 1 and 2), the collar 70 is receivedin the recess 46 and its lateral surface bears on the cylindrical baseof the recess 46. The bulges 44 of the legs are then pressed against theinner surface of the tube 16. Thus, the member 66 is held centred alongthe axis X--X by cooperation with the wall of the body of the syringe.

The member 66 includes an axial passage 72 passing right through it.This passage includes, at the front, a cylindrical portion 74 which iscontinued by a portion 76 whose cross section decreases progressivelytowards the rear. This portion 76 is defined by a truncated surfacewhose cross section, at its narrowest end, is substantially equal tothat of the needle 22.

As is represented in FIG. 2, before the syringe is used, the rear end 22of the needle extends inside the passage 72, so that the end of theneedle is completely covered by the member 66.

The rear plunger 14 includes an elongate pusher 78 with a cruciformcross section and has at its rear end a plate 80 for supporting theoperator's thumb. At its opposite end there is an axial seat 82 which isopen to the front and is used for receiving the rear end 22B of theneedle upon completion of injection. This seat 82, of elongate shapealong the axis X--X, has a circular cross section. It is delimited by acylindrical wall 84 equipped with a calibrated vent 86.

The wall 84 has on the outside, at its front end, a helical flange 88for engaging and fixing a cup-shaped end membrane 90. This membranecloses off the principal front opening of the seat 82 and constitutes atransverse wall adapted to slide in a leaktight manner inside the tube16.

As is represented in FIG. 1, the fluid to be injected 92 is arrangedinside the tube 16 in a space delimited by the membrane 90 of the rearplunger and an intermediate plunger 94. The intermediate plunger 94includes a perforatable transverse wall 96 surrounded by a lateralsleeve 98 integral therewith and equipped with external peripheral ribsin order to ensure leaktightness of the liquid and the gas between thisand the internal lateral wall of the tube 16. The intermediate plunger94 is initially applied against the end of the needle protector. Thewall 96 and the sleeve 98 delimit, to the front, a cup 100 in which ispartially received the rear end of the member 66, which projects fromthe legs 40.

The front end of the tube 16 is fitted in the sleeve 28 and is heldthere by snap-locking. The peripheral groove 30 being provided slightlyto the rear in relation to the transverse wall 20, the latter delimits,with the front end of the tube 16, an annular channel 102 which isarranged immediately to the rear of the wall 20 and whose base is formedby the sleeve 28. The width of the channel 102, measured along the axisX--X, is substantially equal to twice the width of the bulges 44measured along this same axis. At the front, the channel 102 isdelimited by a shoulder 103 formed in the thickness of the sleeve 18.The depth of the hollow space formed by the channel 102 is substantiallyequal to the height of the projections formed by the bulges 44.

Moreover, a protective cap 104 for the needle 22 is fitted inside thesleeve 28 and covers the injection end 22A of the needle.

The syringe is assembled in the following way.

The needle holder 18 is stuck on the needle 22. The protector 36 ismounted through the front wall by engagement of the legs 40 in thepassages 34. It is arranged in such a way that the front protection ring38 surrounds the stud 32 and the legs 40 extend along the rear part ofthe needle 22. The member 66 is then put into place in the recess 46 byelastic deformation of the end of the legs 40. The member 66 is held inposition by the elasticity of the legs 40 whose free ends tend, as aresult of their design, to approach the end 22B of the needle. The frontcap 104 is then put into place by being engaged in the sleeve 28.

The needle holder 18, thus equipped with the cap 104 and the member 66,can be manipulated without risk of damage to the ends of the needle, thelatter being protected at both ends. In particular, it can bedistributed on assembly lines in vibratory bowl feeders.

In parallel with the assembling of the needle holder, the tube 16 isequipped with the grip member 25. It is filled with the fluid 92arranged between the intermediate plunger 94 and the actuating plunger14. The needle holder 18 is put into place by being snap-locked onto thefront end of the tube 16, as is represented in FIG. 1.

The introduction of the legs 40 into the tube 16, upon assembly of theneedle holder on the tube, is easy because the legs 40 together with themember 66 form a single coherent element whose external diameter(diameter measured in the area of the bulges 44) corresponds exactly tothe internal diameter of the tube 16.

In order to proceed with the injection, the operator removes the cap104. In a customary manner, the operator then uses his thumb to exertpressure on the rear plunger 14 in the direction of the arrow F1,pressing on the tabs 27 with index finger and middle finger.

The pressure thus exerted, transmitted by way of the liquid 92 to theintermediate plunger 94, provokes the displacement of the latter, alonga travel marked C1, towards the proximal end 22B of the needle. Thelatter perforates the wall 96 of the intermediate plunger during themovement of the latter. The displacement of the intermediate plunger 94is accompanied by the forward displacement of the needle protector 36.

During driving, the member 66 is driven forwards by the needle protector36 in the recess 46 in which it is held. This is because the legs 40 areapplied along the bulges 44 on the lateral wall of the tube 16, therebyholding the member 66 in the recess 46.

Moreover, during the movement of the member 66, the wall 16 ensures, byway of the legs 40, that it is centred and axially guided in order toguarantee its displacement strictly along the axis X--X.

During the joint movement of the intermediate plunger 94 and the member66, the rear end 22B of the needle first comes into contact with thetruncated surface 76. The latter ensures, as the displacement of themember 66 proceeds, progressive centring of the end 22B of the needle.It additionally provides axial guiding of the needle. Thus, when therear end 22B of the needle emerges from the member 66, the portion ofthe needle arranged inside the body extends strictly along the axisX--X. It is held there by the end of reduced cross section of thepassage 72. The rear end 22B of the needle thus perforates the wall 96while still being held laterally by the member 66 arranged slightly infront on the needle.

In these conditions, the perforation of the intermediate plunger 94takes place axially and in the central part thereof, therebyguaranteeing easy subsequent displacement of the plunger 94 on the wholeinner portion of the needle 22.

The displacement of the intermediate plunger 94 impaled on the needle 22is stopped at the end of the travel C1 when the bulges 42 come intoabutment on the stud 32, as is represented in FIG. 3. For this purpose,the bulges 42 are dimensioned in such a way that the protector 36 isheld in its retracted position in FIG. 3 in which the ring 38 extends inthe sleeve 18 despite the pressure exerted by the intermediate plunger.

The travel C1 corresponds to the purging of the syringe. In fact, thedisplacement of the rear plunger 14 while the intermediate plunger 94 isperforated by the needle ensures evacuation of the air contained in theneedle and the flow of a small quantity of the fluid 92 through thelatter.

After this purge, the injection end 22A of the needle is introduced intothe patient's tissue.

The fluid 92 is then injected through the needle 22 under the effect ofthe pressure on the rear plunger 14 which is driven in along a travel C2as far as the position represented in FIG. 4. In this position, the bulkof the fluid 92 is injected and the membrane 90 comes into contact withthe rear surface of the intermediate plunger 94.

The continued pressure exerted by the operator on the rear plunger 14then causes disengagement of the bulges 42 by means of elasticdeformation of the legs 40. This results in the forward displacement ofthe protector 36. When the ring 38 comes into contact with the patient'sskin, the travel of the protector is stopped, and continuedapproximation, along a travel C3, of the thumb pressing on the plate 80and of the other fingers held against the tabs 27, causes the syringebody 12 to reverse in the direction of the arrow F2 (FIG. 5).

It will be appreciated that the reverse movement of the body 12 causesextraction of the injection needle 22 from the patient's body.

It is also possible, by simply pulling on the syringe body, to extractthe needle from the patient's tissue while the syringe is in theposition represented in FIG. 4. The driving of the rear plunger 14 intothe syringe body is in this case continued with the syringe disengagedfrom any contact with the patient.

Furthermore, the rear end 22B of the needle pierces through the membrane90 and is received in the seat 82. On account of the presence of themember 66, the perforation of the membrane 90 takes place strictly alongthe axis X--X.

In the position represented in FIG. 5, the bulges 44 carried externallyby the free end of the legs 40 are arranged opposite the annular channel102. Moreover, in this position, the member 66 lies with its front faceabutting on the stud 32 and the front face 20. It is thus immobilizedaxially.

During the final phase of driving the plunger 14 along a travel C4, theneedle protector 36 is displaced forwards under the action of thepressure of the rear plunger 14 transmitted by the intermediate plunger94 which is still in contact with the free end of the legs 44. For thispurpose, the rear end of the member 66 which projects in relation to thelegs 40 withdraws into the cup 100, thus allowing the intermediateplunger 94 to slide despite the immobilization of the member 66.

While the member 66 is immobilized, the cam surfaces 52 formed at therear of the recess 46 cooperate with the collar 70 forming a camfollower in order to space the free ends of the legs apart. As a resultof this spacing apart, the bulges 44 are received in the annular channel102, as is represented on a larger scale in FIG. 7.

In this position, the projections 50 bordering the recess 46 at the rearrest on the lateral surface of the collar 70, thereby ensuring positiveretention of the bulges 44 inside the annular channel 102 and positiveblocking of the needle protector 36.

Moreover, the projections 50 are received in the peripheral groove 71 ofthe collar, thereby ensuring axial connection of the member 66 and ofthe needle protector 36. Thus, even if the needle protector is caused todisplace slightly axially (along the length of the annular channel 102),the member 66 is entrained and remains opposite the bulges 44, whichpermits permanent positive retention of the bulges 44 in the channel102. Thus, the ends of the legs 40 cannot be released, which guaranteesthe locking of the needle protector 36 in its active protectionposition.

In FIGS. 6 and 7, the protector 36 is in the active protection positionand extends around the injection end 22A of the needle. The front faceof the protection ring 38 is thus situated slightly in front of the end22A of the injection needle, prohibiting any contact between the latterand an external element and thereby preventing any risk of the operatorbeing contaminated by a stick injury.

It will be appreciated that the bulges 44 engaged in the channel 102between the shoulder 103 and the end of the tube 16 hold the protector36 firmly in the protection position, thereby prohibiting any accidentalretraction. This hold is in fact guaranteed by the presence of themember 66, whose collar 70 keeps the ends of the legs 40 spaced apart.

The membrane 90 having been perforated by the rear end 22B of theneedle, the syringe is rendered unavailable for further use. The reasonis that this perforation prohibits the suction effect normally obtainedinside the body upon withdrawal of the rear plunger on account of thepresence of the vent 86. Likewise, the rear plunger, once perforated,does not allow expulsion, via the injection needle 22, of any liquidre-introduced into the syringe body.

It will be appreciated that in a syringe such as the one described here,the member 66 guarantees a correct perforation of the intermediateplunger 94. This is because the end 22B of the needle, guided by thetruncated surface 76, penetrates at the centre of the plunger 96 andalong the axis X--X of the syringe.

In a syringe deprived of a needle protector, the guide member 66 bearsalong its lateral wall directly on the inner surface of the tube 16,along which it slides upon actuation of the syringe.

In the example described, the member 66 is initially arranged around theend 22B. However, the member 66 can be arranged on the needle slightlyin front of its rear end, while still correctly exercising its guidefunction for the rear end of the needle.

Moreover, in the case of a syringe in which the needle holder 18 isequipped with sealing means between the wall 20 and the legs 40, theintermediate plunger 94 is omitted. However, the member 66 isadvantageously kept in order to ensure, in the position analogous tothat in FIG. 4, perforation of the transverse wall 90 of the rearplunger strictly along the axis X--X of the syringe, thus guaranteeingcorrect axial penetration of the needle in the seat 82.

In a variant which is not shown, the projecting elements formed by thebulges 44 and the associated complementary recessed element formed bythe annular channel 102 are inverted. Thus, the legs include recessesexternally, whilst the syringe body has complementary projections with aview to holding the protector in its active protection position.

In this variant too, the member 66 ensures positive retention of theengagement of the associated projecting and recessed reliefs when theneedle protector is in its active protection position.

According to another variant represented in FIG. 8, the rear plunger 14includes, in front of the support plate 80 for the operator's thumb,snap-locking projections 150 adapted to cooperate with an internalannular shoulder 152 formed at the rear end of the syringe body 12 andcarried, for example, by the grip member 25. This shoulder delimits aradial face 152A oriented towards the front of the syringe and continuedby a ramp 152B directed towards the rear of the syringe.

These snap-locking projections 150 have, for example, the shape of atriangle, of which the face 154 disposed in front, viewed in thedirection of driving, constitutes a ramp, and of which the rear face 156forms a shoulder adapted to bear on the internal peripheral shoulder 152of the body after passing the latter, as is represented by a broken linein FIG. 8.

It will be appreciated that after the rear plunger has been fully driveninto the syringe body, the snap-locking projections 150 fit elasticallyin front of the peripheral shoulder 152. They thereby ensure retentionof the rear plunger inside the syringe body. For this reason, theyensure, by way of the intermediate plunger 96, a positive retention ofthe rear ends of the needle protector in its active protection position.

Moreover, the snap-locking projections and the internal shoulderadvantageously have profiles adapted to permit the emission of anacoustic signal when the peripheral shoulder is passed by thesnap-locking projections. For this purpose, the snap-locking projectionsinclude, for example, as is represented in FIG. 9, an elastic blade 160which is compressed when the peripheral shoulder 152 is being passed andwhich is released after the latter has been passed.

The existence of the acoustic signal allows the user to verify that therear actuating plunger has been sufficiently driven into the syringebody to ensure that the needle protector is indeed in front of theinjection end of the needle.

What is claimed is:
 1. Injection syringe (10) of the type whichincludes, on the one hand, an elongate syringe body (12) comprising atube (16) and a front wall (20) equipped with an injection needle (22),and, on the other hand, a rear actuating plunger (14) which is mountedso as to be displaceable in the tube (16), which syringe additionallyincludes a mobile protector (36), for the injection end (22A) of theneedle, displaceable between a retracted position in the syringe body,behind the injection end (22A) of the needle, and an active protectionposition in which the front end of the protector (36) is situated infront of the injection end (22A) of the needle, the protector (36) andthe syringe body (12) including associated projecting and recessedreliefs (44, 102) for maintaining the protector (36) in its activeprotection position, characterized in that it includes, inside thesyringe body (12), a member (66) for positive retention of theengagement of the said associated projecting and recessed reliefs (44,102) when the needle protector (36) is in its active protectionposition.
 2. Syringe according to claim 1, characterized in that theprotector (36) includes at least one cam surface (52) cooperating withat least one cam follower (70) carried by the positive retention member(66) in order to effect engagement of the said associated projecting andrecessed reliefs (44, 102) during the final phase of the displacement ofthe protector (36).
 3. Syringe according to claim 2, characterized inthat the protector (36) includes legs (40) which pass through thesyringe body (12) and whose free end extends inside the syringe body,the associated projecting and recessed reliefs (44, 102) being carriedby the free ends of the legs (40) and by the syringe body (12), thepositive retention member (66) including means (70) for positive spacingapart of the free ends of the legs (40) towards the syringe body (12).4. Syringe according to claim 3 taken together, characterized in thatthe positive retention member (66) is disposed axially in the syringebody (12), between the legs of the needle protector, and the saidpositive spacing means are formed by a collar (70) carried by the saidpositive retention member (66), which collar (70) is adapted tocooperate, when the protector (36) is in its active protection position,with projections (50) carried internally by the free ends of the legs(40), the said projections (50) each continuing a cam surface (52)carried by a leg (40) with which the said collar (70) cooperates forminga cam follower during the final phase of displacement of the protector.5. Syringe according to claim 4, characterized in that the said collar(70) has a groove (71) for receiving the said projections (50). 6.Syringe according to claim 5, characterized in that the legs (40)include means (46) for driving the positive retention member (66) duringthe displacement of the protector (36) from its retracted position toits active protection position, and the syringe body (12) includes anabutment (20, 32) for stopping the positive retention member (66) beforecompletion of the displacement of the protector (36) as far as itsactive protection position.
 7. Syringe according to claim 6,characterized in that the said means for driving the positive retentionmember (66) comprise a countersink (46) formed in the inner surface ofthe legs (40) and in which the said collar (70) is received, whichcountersink (46) is delimited at the rear on each leg (40) by a camsurface (52).
 8. Syringe according to claim 1, characterized in that therear plunger (14) and the syringe body (12) include complementary meansadapted to produce an acoustic signal when the plunger (14) has beendriven in sufficiently for the needle protector to be in its activeprotection position.